PURPOSE: To prevent revolution of an equalizer arranged between front and rear plate springs and occurrence of a slip event when its occurrence is forecast in a rear 2-shaft suspension for a trailer in which the plate springs are mounted on each shaft.

CONSTITUTION: A 4-spring short rocker type suspension system mounts the front, center, and rear hangers 2W4 and arranges each plate springs 5 and 6 between an equalizer 17 which is mounted on the center hanger 3 so as to freely revolve and the hangers 2W4 so that they can be slide-contacted in each end. Besides, both the hangers 2 and 3 and front and rear wheels 7 and 8 are connected by torque rods 15 and 16. In the said system, a hole is provided near the center of revolution of the equelizer 17 of the center hanger 3 and a bolt 19 for the equalizer stopper can be inserted in this hole. This bolt 19 is inseted only when the occurrence of a slip event is forecast.